1. Technical Field
The present invention relates to a polishing media, a method for producing a polishing media, and a polishing method.
2. Related Art
As one of the methods for polishing a surface of a work (a material to be polished), barrel polishing is used. Barrel polishing is performed for the purpose of, for example, deburring, chamfering, surface finishing, or the like of a surface of a work made of a ceramic or a metal.
Barrel polishing is performed by putting a work and a polishing media in a barrel polishing tank and stirring these. When stirring the work and the polishing media, the work and the polishing media collide or rub against each other, whereby a surface of the work is polished.
As a material of the polishing media to be used for barrel polishing, a ceramic material is used because the material is required to have a high hardness. JP-A-5-293753 discloses a barrel stone made of aluminum oxide, zirconium oxide, silicon carbide, or the like.
In the meantime, when the work is small or has a complicated shape including a concave portion, a portion where contact between the work and the polishing media is not sufficient is generated, and polishing is not sufficient in the portion. Therefore, when barrel polishing is performed for such a work, it is necessary to use a small polishing media corresponding to the size or the shape of the work.
However, the small polishing media has a mass decreased to an extent corresponding to the decrease in the size and also the collision energy for the work is decreased, and therefore, a polishing force (polishing efficiency) is lacking at all. Due to this, it takes a lot of time to polish the work. Moreover, a ceramic material has a specific gravity less than a metal material or the like, and therefore the mass of the polishing media is further decreased.
On the other hand, JP-A-63-267157 discloses a media for barrel polishing obtained by providing an abrasive material layer containing superhard coating particles such as diamond or CBN on a surface of a metal ball core. If a polishing media has such a configuration, the mass of the media can be increased without decreasing the hardness of the surface, and therefore, even if the size of the polishing media is decreased, the polishing force hardly decreases.
In the barrel polishing, polishing proceeds in such a manner that a work and a polishing media rub against each other and abrade each other. However, in the case of the media disclosed in JP-A-63-267157, when the abrasion of the polishing media proceeds and at the time when the abrasive material layer is worn away, the polishing force is lost. Accordingly, there is a problem that the life of the polishing media is short.